Jest is running thousands of tests at Facebook at all times, either through continuous integration or invoked by engineers manually during development. This worked well for years even as the people working on Jest moved on to other projects within Facebook.| jestjs.io
Today we're announcing a switch to major revisions for Jest with Jest 11.0 being the first major release. Jest has been used by Facebook engineers and on our continuous integration systems for years and we believe Jest has been way beyond a “1.0 release” for a long time. This is similar to a change the React team has made.| jestjs.io